Pro-Palestinian activists have broken into RAF Brize Norton and sprayed two military planes with red paint in a security breach.
The Ministry of Defence strongly condemned the "vandalism of Royal Air Force assets" and said it was working closely with the police.
Footage posted online by Palestine Action on Friday shows two people inside the Oxfordshire airbase in darkness, with one riding on a scooter up to the Airbus Voyager air-to-air refuelling tankers and appearing to spray paint into its jet engine.
The group said the activists were able to "evade security" and claimed they had put the supply planes "out of service".
Speaking before the details were confirmed, cabinet minister Lisa Nandy told the BBC the break-in was "deeply concerning" and that the government would be "cracking down" on people who "think they can treat national security with that level of disregard".
